Hydraulic fracturing (“fracing”) is a well known technique for releasing oil and natural gas from underground reservoirs within rock formations having a limited permeability. For example, fracing is often used to release oil and natural gas, such as natural gas or oil, from shale formations.
Fracing is a well completion technique performed after the drilling of the wellbore, which in the case of releasing natural gas from shale, is commonly a horizontal wellbore, although occasionally the wellbore is vertical. Fracing fluid, which is primarily water and chemicals that form a viscous gel, is pumped into the well to create fractures within the surrounding rock. The viscous gel carries a “proppant” into the fractures, such that when the pumping stops, the fractures remain substantially open and allow the oil and natural gas to escape into the wellbore.
One typical proppant is “frac sand.” Frac sand is normally high purity silica sand with grains having a size and shape capable of resisting the crushing forces applied during the closing of the fractures when the hydraulic force provided by the pumping is removed. However, given that frac sand contains a high proportion of silica, the loading, transportation, and unloading of frac sand presents significant safety challenges.
The United States Occupational Safety and Health Administration (“OSHA”) lists silica as a carcinogen. In particular, the exposure and inhalation of silica dust has been linked to silicosis, which is an irreversible lung disorder characterized by inflammation and scarring of the upper lobes of the lungs. The best, and perhaps only way, to reduce or eliminate the threat of silicosis is to carefully control worker exposure to silica dust.
OSHA lists a number of different ways to limit worker exposure to silica dust, including limiting worker time at a worksite, limiting the number of workers at a worksite, watering roads and other worksite areas, enclosing points where silica dust is released, and requiring workers to wear respirators. These techniques do not, at least on their own, provide a complete solution to the problem of controlling silica dust. Furthermore, these existing techniques, while commendable, are nonetheless burdensome, time-consuming, inefficient, and impractical.